Yes, JUDICIARIES is a Scrabble word!

Letter values in Scrabble US: J 8, U 1, D 2, I 1, C 3, I 1, A 1, R 1, I 1, E 1, S 1.

Is it a valid word?

JUDICIARIES is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

persons who administer justice
the system of law courts that administer justice and constitute the judicial branch of government

Also: judicial system.